This invention relates to a composition for anchoring materials in or to concrete or masonry. More particularly, this invention relates to an alkylacrylate ester/methacrylic acid copolymer composition for anchoring materials in or to concrete or masonry.
Many applications require that a material be anchored in or to concrete or masonry. For example, anchor bolts are employed in various fields of engineering as strengthening or reinforcing members in rock formations, or concrete or masonry structural bodies. The bolts, which are typically metallic, are inserted into holes in the rock formations, or concrete or masonry structural bodies, are fixed or anchored therein by means of an anchor composition. Typically, the anchor composition cures or hardens (polymerizes) to form a strong bond between the rock formation, or the concrete or masonry structural body and the bolt. In concrete or masonry, anchor bolts are used for reinforcement. Anchor bolts are also used for attaching objects to concrete or masonry. Objects that have been attached to concrete or masonry using anchor bolts include, but are not limited to, electrical conduits, panels, piping and wall sections. Adhesive anchors are preferred over mechanical anchors for anchoring in soft concrete or masonry because adhesive anchors place less stress on the concrete or masonry. As used herein, the term xe2x80x9cmasonryxe2x80x9d shall include, but is not limited to, stone, brick, ceramic tile, cement tile, hollow concrete block and solid concrete block.
A useful anchor composition should be inexpensive, provide for a strong bond between the concrete or masonry and the material to be anchored to the concrete or masonry, be easy to dispense at the location of use and have a long storage shelf life. Some anchor compositions that have been used include compositions based on aromatic vinyl esters, aromatic polyesters and epoxies. These compositions can be expensive or may not provide the desired bond strength between the concrete or masonry and the material that is anchored in or to the concrete or masonry.
An example of the anchor compositions of the prior art is found in Japanese Patent Application Sho59-122762 (xe2x80x9cJP ""762xe2x80x9d). Generally, JP ""762 discloses an anchor composition comprising a monomer, a polymer soluble in the monomer, aggregate and a hardening agent. With respect to the monomer component, JP ""762 discloses a broad range of compounds which include methacrylate esters. With respect to the polymer component, JP ""762 discloses a similarly broad range of compounds which includes methacrylate esters and acrylic acid, and further discloses the use of copolymers. Moreover, JP ""762 discloses a composition comprising 70 to 95% by weight of the monomer and 5 to 30% by weight of the polymer.
Notably, however, JP ""762 fails to recognize the unexpected and surprising properties of fast cure time and pull out strength realized by the selection of a methacrylate ester monomer and a copolymer of a methacrylic ester and methacrylic acid in the formation of an anchor composition as shown herein. The unexpected and surprising results achieved by this particular combination is shown in certain of the examples set forth below in which significantly shorter cure times and greater pull out strengths are exhibited by the compositions of the present invention as compared to other compositions which fall within the scope of the broad disclosure of JP ""762. As a result, the composition of the present invention represent a novel and unobvious advancement over the prior art.
The present invention provides a composition for anchoring materials in or to concrete or masonry that comprises from about 20% to about 90% by weight of the entire composition of a alkylacrylate ester monomer and an alkylacrylate ester/methacrylic acid copolymer; a free-radical catalyst; and a filler.
In a preferred embodiment, the present invention provides a composition for anchoring materials in or to concrete or masonry that is made by mixing a first composition and a second composition. The first composition comprises from about 20% to about 90% by weight of the entire composition of a methacrylate ester monomer and methacrylate ester/methacrylic acid copolymer; and a filler. The second composition comprises a free-radical catalyst.
The present invention provides an anchor composition for anchoring materials in or to concrete or masonry. The materials to be anchored in or to concrete or masonry include, but are not limited to, metallic objects, such as steel bolts, ceramics, other concrete or masonry objects, plastics, glasses and woods.
The composition comprises methacrylate ester monomer, a methacrylate ester/methacrylic acid copolymer, a free-radical catalyst and a filler. It may also be desirable to include in the composition a thixotropic agent, a chain transfer agent, a free-radical inhibitor, a fragrance, an activator, a promoter and/or a pigment. It is also recognized that other components known to those skilled in the art may be included in the composition. Such components may include, but are not limited to, antifoaming agents, wetting agents, fungicides, impact modifiers, crosslinking agents and coupling agents.
The composition may be dispensed using various methods known to those skilled in the art. For example, the composition may be dispensed using a dual cartridge device similar to a caulk gun, or the composition may be dispensed using a glass or film capsule. The composition may also be dispensed in bulk from bulk containers using meter-mix equipment, which is known to those skilled in the art. U.S. Pat. Nos. 4,651,875, 4,706,806 and 4,729,696, the disclosures of which are hereby incorporated by reference, are directed to glass capsules. It is recognized that the amounts of the various components of the anchor composition may vary depending on the type of dispensing system used. In preferred dispensing methods, the anchor composition is formed by the mixing of a first composition and a second composition. Typically, the mixing occurs immediately before the anchor composition is to be used. For example, when the anchor composition is dispensed using a dispensing gun, the first composition and the second composition, which are contained in separate cartridges of the dispensing gun, may be mixed as they are ejected from the cartridges and applied to either the concrete or masonry, the material to be anchored to the concrete or masonry or both. Similarly, when the anchor composition is dispensed using a glass capsule, the capsule is typically comprised of two chambers that contain the first composition and the second composition respectively. When the glass capsule is crushed, the two chambers are crushed and the contents are allowed to mix, forming the anchor composition. Last, when the anchor composition is dispersed in bulk, a first composition and a second composition may be stored in separate bulk containers and combined through pumping with mixing in the appropriate ratio to make the anchor composition.
The anchor composition preferably contains a methacrylate ester monomer and a methacrylate ester/methacrylic acid copolymer. It is preferable if the methacrylate ester/methacrylic acid copolymer has a weight-average molecular weight in the range of about 10,000 to about 60,000. More preferably, the copolymer has weight-average molecular weight in the range of about 20,000 to about 40,000.
In general, the methacrylate ester/methacrylic acid copolymer is soluble in the methacrylate ester monomer to form a solution. The ratio of copolymer to monomer is in the range of about 1 to 9 to about 2.5 to 1 by weight. Preferably, the copolymer to monomer ratio is in the range of about 1 to 4 to about 1 to 1.5 by weight. More preferably, the copolymer to monomer ratio is in the range of about 1 to 4 to about 1 to 2.5 by weight.
As used herein, the phrase xe2x80x9cmethacrylate ester monomerxe2x80x9d shall mean esters of methacrylic acid, including, but not limited to, the methyl, ethyl, propyl, isopropyl, butyl, tert-butyl, cyclohexyl, 2-ethylhexyl and tetrahydrofurfuryl esters of methacrylic acid. As used herein the phrase xe2x80x9cmethacrylate ester/methacrylic acid copolymerxe2x80x9d shall mean a copolymer which can theoretically be made from methacrylate ester and methacrylic acid monomers.
The copolymer may be a random, block, graft or alternating copolymer. The polymer also can be linear or branched and can be based on two or more different methacrylate ester monomers. It is also contemplated that the methacrylate ester monomer component may be a mixture of different methacrylate monomers, and the methacrylate ester/methacrylic acid copolymer component may be a mixture of more than one copolymer.
Generally, the monomer/copolymer combination is present in the anchoring composition in the range of about 20% to about 90% by weight of the entire composition. Preferably, the monomer/copolymer combination is present in the anchoring composition is an amount in the range of about 20% to about 60%. More preferably, the monomer/copolymer combination is about 40% to about 45% by weight of the entire composition when the composition is dispensed using a dispensing gun, and about 20% to about 30% by weight of the entire composition when the composition is dispensed using a glass capsule.
The anchor composition also comprises a free-radical catalyst, which starts the free-radical polymerization of the methacrylate ester and methacrylic acid monomers in the composition, which results in a hardened or cured composition. Examples of free-radical catalysts include, but are not limited to, peroxides, such as the diacyl peroxides, hydroperoxides, peresters, peracids and radiant energy or thermal energy, i.e. ultraviolet light and heat. Examples of specific free-radical catalysts include, but are not limited to, dibenzoyl peroxide, cumene hydroperoxide, tertiary butyl peroxide, dicumyl peroxide, tertiary butyl peroxide acetate, tertiary butyl perbenzoate and ditertiary butyl azodiisobutyronitrile. Examples of the diacyl peroxides include, but are not limited to, dibenzoyl peroxide, succinic acid peroxide, dilauroyl peroxide, didecanoyl peroxide and diisononanoyl peroxide. The most preferred free-radical catalyst is dibenzoyl peroxide. It is also contemplated that more than one free-radical catalyst may be used in the composition. The free-radical catalyst is usually present in the composition in the range from about 0.5% to about 10% by weight of the entire composition. Preferably, the catalyst is found in the composition in the range of about 1% to about 5% by weight of the entire composition. Even more preferably, the free-radical catalyst is about 2% by weight of the entire composition.
The composition can also include a catalyst activator (also called an initiator). Throughout this application, the terms xe2x80x9cactivatorxe2x80x9d and xe2x80x9cinitiatorxe2x80x9d are used interchangeably. Representative activators include an aldehyde-amine condensation product, organic sulfonyl chlorides, tertiary amines or mixtures thereof. For example, such a condensation product can be made from butyraldehyde and a primary amine, such an amine being, for example, aniline or butylamine. Also suitable as activators are tertiary amines such as N,N-dimethyl aniline, N,N-dimethyl toluidine, N,N-diethylaniline, N,N-diethyl toluidine, N,N-bis(2-hydroxyethyl)-p-toluidine, N,N-bis(hydroxypropyl)-p-toluidine and the like. A preferred activator is N,N-bis(2-hydroxyethyl)-p-toluidine.
The composition can also include a promoter, which is an organic salt of a transition metal such as cobalt, nickel, manganese or iron naphthenate, copper octoate, copper acetylacetonate, iron hexoate or iron propionate.
In concrete anchoring, much of the heat of polymerization is lost to the mass of concrete. Therefore, activators such as N,N-bis(2-hydroxyethyl)-p-toluidine may be used to achieve the desired rapid cure times. However, when anchoring in hollow concrete blocks, portions of the anchor composition may not contact the concrete, and heat loss to the surroundings is minimized, which can result in incomplete curing of the bulk anchor composition. In such cases, it may be preferable to add a chain transfer agent to the composition. Chain transfer agents are discussed below. The amount of activator and chain transfer agent that gives acceptable cure speeds, shelf life and bulk cure properties for a particular application and composition can be determined by those skilled in the art by routine optimization.
The initiators and activators, if part of the composition, can be added in an amount up to about 10% by weight of the entire composition. Preferred amounts are in the range of about 0.01 to about 1.5%. Promoters are typically used in amounts up to about 0.5% by weight of the composition, and preferably about 1 part per million to about 0.5% by weight of the entire composition.
The anchor composition may also comprise a thixotropic agent. A thixotropic agent that is added to a composition causes the composition to become more fluid, i.e. less viscous, when agitated, stirred or mixed or otherwise subjected to such shear forces. It is useful to include a thixotropic agent in the anchor composition to insure that the composition has the desired viscosity during application and after the composition is applied. In addition, a thixotropic agent may be added to an anchor composition to prevent the settling of other solid components of the composition and to increase the viscosity of the composition. The thixotropic agent also facilitates dispensing of the composition because when a shear force is applied, e.g. expulsion of the composition from a dispensing gun, the thixotropic agent makes the resulting composition less viscous, and therefore, more easy to expel from the cartridges of the dispensing gun. The thixotropic agent may be found in the anchor composition in an amount in the range of 0.5% to about 10% by weight of the entire composition. Preferably, the thixotropic agent is found in the composition in an amount in the range of about 2% to about 7% by weight of the entire composition. Most preferably, the thixotropic agent is about 5% when the composition is dispensed from a dispensing gun. Typically, no thixotropic agent is needed when the anchor composition is dispensed using a glass capsule. An example of a suitable preferred thixotropic agent is fumed silica. Also contemplated are the various silicas made by the various methods known in the art, including pyrolysis of silicon tetrachloride and precipitation. Other suitable thixotropic agents include the various organoclays and various fibers. In some anchor compositions, the thixotropic agent may also be considered a filler. A suitable silica thixotropic agent is Aerosil(copyright) R202, which may be obtained from the Degussa Corporation of Ridgefield Park, N.J. It is also contemplated that more than one thixotropic agent may be used in the anchor composition.
The anchor composition of the present invention also comprises one or more fillers. Fillers are typically added to compositions for various reasons, including to reduce shrinkage of the composition that may occur during polymerization and to reduce the cost of the composition, as fillers replace a portion of the more expensive components of the anchor composition. The filler may also provide for improved bond strength of the anchor composition when polymerized and help to prevent the settling out of other particulate materials in the composition. Generally, the filler is an inert, inorganic, solid, particulate compound. By inert it is meant that the filler does not detrimentally interact with any other component of the composition. Examples of suitable fillers include, but are not limited to, crushed glass, glass beads, quartz, silica, limestone, alumina, various clays, diatomaceous earth and other materials such as mica, flint powder, kryolite, alumina trihydrate, talc, sand, pyrophyllite, blanc fixe, granulated polymers such as polyethylene, hollow glass and polymer beads, zinc oxide, novaculite, calcium sulfate and mixtures thereof. Preferred fillers are quartz, glass and silica. Fillers may be treated with coupling agents to improve bonding to the polymer matrix. Examples of coupling agents which may be used to treat the fillers are silanes, titanates and zirconates.
Generally, fillers can be found in the composition in an amount in the range of 10% to about 90% by weight of the composition. In certain preferred embodiments in which the anchor composition is dispensed by means of a dispensing gun, fillers are found in the range of about 20 to about 80% by weight of the composition, and more preferably, about 40 to about 65% by weight of the composition. In certain preferred embodiments in which the anchor composition is dispensed by means of a glass capsule, fillers, including the glass or film capsule, are found in the range of about 40 to about 90% by weight of the composition, and more preferably, about 65 to about 80% by weight of the composition.
The exact particle size of the filler will depend on the desired consistency of the composition and the method for dispensing the anchor composition. For example, fillers having a large average particle size (300 microns and larger) may clog static mixers that are used in dispensing systems such as dispensing guns. On the other hand, fillers having a large particle size can be used in glass capsules. Preferred particle sizes are about 50 microns or larger. However, in cases where a filler is used to prevent the settling out of other particulate matter in a composition, a particle size smaller than 50 microns may be desired. It is also recognized that a filler having a particle size less than 50 microns may be used in combination with other fillers, some having particle sizes greater than 50 microns.
Preferred fillers for use in anchor compositions that are to be dispensed using a dispensing gun have average particle sizes in the range of about 50 to about 275 microns, and even more preferably in the range of about 150 to 200 microns. Preferred fillers for use in anchor compositions that are to be dispensed using a glass capsule have average particles sizes in the range of about 100 to about 3,000 microns, and even more preferably in the range of about 1200 to 2000 microns.
The anchor composition may also include a free-radical chain transfer agent. Free-radical chain transfer agents are included in anchor compositions to facilitate polymerization. Chain transfer agents also have the effect of limiting the molecular weight of the polymers that are formed by the polymerization. The use of a free-radical chain transfer agent provides for an acceptable polymerization speed and for more complete polymerization of the anchor composition, particularly when a large mass of the composition is to be polymerized. Preferred free-radical chain transfer agents include mercaptans such as dodecyl mercaptan. In addition, other chain transfer agents are known to those skilled in the art, and a suitable free-radical chain transfer agent may be readily selected by those skilled in the art. In certain preferred embodiments in which the anchor composition is dispensed by means of a dispensing gun, the free-radical chain transfer agent may be found in the range of about 0 to about 4% by weight of the composition, and more preferably, about 0.1 to about 2% by weight of the composition. In certain preferred embodiments in which the anchor composition is dispensed by means of a glass capsule, the free-radical chain transfer agent may be found in the range of about 0 to about 5% by weight of the monomer/polymer composition, and more preferably, about 0.5 to about 4% by weight of the monomer/polymer composition.
The anchor composition may also include a free-radical inhibitor. A free-radical inhibitor is added to the composition to inhibit the polymerization of monomers in the composition until such polymerization is desired. The addition of a free-radical inhibitor also increases the storage shelf life of the anchor composition. In certain preferred embodiments in which the anchor composition is dispensed by means of a dispensing gun, the free-radical inhibitor may be found in the range of about 0 to about 0.1% by weight of the composition, and more preferably, about 0.005 to about 0.05% by weight of the composition. In certain preferred embodiments in which the anchor composition is dispensed by means of a glass capsule, the free-radical inhibitor may be found in the range of about 0 to about 0.16% by weight of the monomer/polymer composition, and more preferably, about 0.02 to about 0.08% by weight of the monomer/polymer composition.
In one embodiment of the present invention, the anchor composition is formed by mixing a first composition and a second composition. The first composition contains the polymerizable monomers and may contain an inhibitor to prevent polymerization of the monomers until desired, and the second composition contains a free-radical catalyst. When the first composition and the second composition are combined, polymerization occurs. Free-radical inhibitors are known to those skilled in the art. A preferred free-radical inhibitor is trimethyl hydroquinone. Other suitable free-radical inhibitors include, but are not limited to, hydroquinone, hydroquinone monomethyl ether, t-butyl catechol and naphthaquinone. It is also contemplated that more than one free radical inhibitor may be employed in the anchor composition.
The anchor composition may also contain a fragrance. A fragrance is used in an anchoring composition to mask any odor of the composition that is thought undesirable or unpleasant. A preferred fragrance is Atlanta Fragrance 16332. Similarly, a pigment may be employed to color the anchoring composition. Suitable pigments are known to those skilled in the art.
In a preferred embodiment the anchor adhesive is made by mixing a first composition and a second composition. The first composition comprises a methacrylate ester monomer, a methacrylate ester/methacrylic acid copolymer and a filler. The first composition may also comprise a thixotropic agent, a chain transfer agent, a free-radical inhibitor, a fragrance, an activator, a promoter and/or a pigment. The second composition contains a free-radical catalyst. The second composition may also include a filler, a thixotropic agent, a fragrance, and/or a pigment. It is also contemplated that both the first composition and the second composition may contain some of the same components.
The ratio of the first composition to the second composition may be in the range of 1 to 1 to about 40 to 1. Preferably, the ratio of the first composition to the second composition is about 10 to 1.
Also provided is a method for anchoring a material in or to concrete or masonry that comprises the steps of delivering the above-described anchor composition to concrete or masonry, the material to be anchored to the concrete or masonry or both; contacting the material to be anchored, the concrete or masonry and the anchor composition; and polymerizing the anchor composition.
The delivery of the anchor composition may be accomplished by any method known to those skilled in the art, including by cartridge in a dispensing gun, by glass capsules or from bulk containers through meter-mix equipment. The composition is applied to either the concrete or masonry, the material to be anchored in or to the concrete or masonry, or both. Then, the concrete or masonry and the material to be anchored to the concrete or masonry are contacted so that both the concrete or masonry and the material to be anchored comes into contact with the anchor composition. The anchor composition is then polymerized.
The following examples are provided to illustrate particular embodiments of the invention and are not intended to limit the scope of the invention or the claims in any manner.